This proposal requests support for a new postdoctoral training program to train MD and PhD researchers to assume leadership roles in developing innovative, high impact research on adherence to medical treatment and chronic illness management that will enhance the health outcomes of children with pediatric chronic conditions. Modern medical treatments have improved the health outcomes of large numbers of children and adolescents with chronic conditions. However, one of the most critical remaining barriers to improving children's health outcomes over the course of their lifetime management of chronic illness is nonadherence to prescribed medical treatment. Nonadherence is defined as the discrepancy between prescribed treatment (medication or other treatments) and what is actually taken by patients. As noted by the World Health Organization (WHO), treatment nonadherence is not only highly prevalent (rates of 50% or greater in pediatric chronic illness populations) but has an extraordinary negative impact on children's health and health care costs. Innovative and clinically relevant research will be needed to close the gap between the health outcomes that are potentially achievable with more optimal treatment adherence and those achieved in current practice. NIH program priorities and requests for applications, scientific consensus conferences, and scholarly reviews have all identified the critical importance of research on pediatric adherence to treatment. A critical barrier to scientific advances in pediatric adherence and chronic illness management research is the shortage of talented, well-trained researchers who are devoting their careers to developing innovative, high impact treatment adherence and chronic illness management research with pediatric populations. One of the most promising ways to address this need and improve child health is to develop innovative interdisciplinary research training programs to train leaders in the field of treatment adherence and chronic illness management research. This is the goal of the proposed program. Specific training innovations will involve the integration of biomedical, behavioral, biostatistics, and health services/outcomes research and are reflected in a comprehensive training curriculum and research opportunities. Research innovations include novel methods of adherence promotion interventions involving technology (telehealth, internet, cell phone) designed to enhance the power and duration of intervention effects and reach diverse populations who cannot easily access traditional clinic-based approaches. Program innovation will also be enhanced by novel research training opportunities to evaluate the comparative effectiveness of adherence promotion interventions in pediatric chronic illness management, to integrate objective methods of adherence measurement (e.g., behavioral and pharmacological) and conduct advanced statistical analyses to evaluate the impact of adherence promotion interventions on children's health outcomes.